This invention relates to a photoelectric switch and, more particularly, to a photoelectric switch of a type having a housing consisting of two plastic shells welded together by ultrasonic welding.
A variety of photoelectric switches, namely photoelectric detectors, which utilize a light source element such as a light emitting diode and a light responsive element such as a photoelectric transistor for detecting the presence or absence of an article in the light path between said light source element and light responsive element are known. The elements are generally accomodated in a common housing, or accomodated each in an independent housing, said housing being made of metal or other opaque material and provided with a window means made of glass or plastic material which is transparent to light.
However, it is difficult to achieve a hermetic or fluidtight seal between the housing and window means. It should be understood that the term "photoelectric switch" is used herein to refer not only to a device comprising a light source element and a light responsive element in a common housing but to a device comprising either a light source element or a light responsive element in a housing. Similarly, the term "light" is used herein to refer to any radiant electromagnetic energy in the far infrared to ultraviolet regions of the spectrum, including, but not limited to visible light.
It is an object of this invention to provide a photoelectric switch including a housing which is provided with a window means as welded thereto fluid-tight by ultrasonic welding.
Another object of this invention is to provide a photoelectric switch which is compact and simple in construction and easy to fabricate at low cost.